At the same time, the Atlantic appears to be transitioning into a period of low hurricane activity. These cycles typically last between 25 to 40 years, and the most recent high activity cycle began in 1995.

In other words, if a La Niña comes together and it turns out the Atlantic is still in a high activity cycle, it could be a busy hurricane season.

At the other end of the spectrum, if a La Niña never develops and the Atlantic is entering a low activity cycle, then hurricanes will be few and far between this year.

If it's another combination where both factors work against one another, we'll likely see a typical hurricane season, which is why the National Hurricane Center has placed a 45 percent probability on just that happening.